Photographic dryer

ABSTRACT

Dryer for continuous web material including conveyor means extending in a generally circular, preferably helical, path and supporting the material on one side from movement along such path, a drying air plenum extending along a substantial portion of the conveyor path and having a wall lying in generally closely spaced parallel relation to such path portion with apertures in the wall for directing air onto the web material supported on the conveyor, an air current generator for supplying air to the plenum. Preferably, the plenum is in the form of an annular chamber defined by two spaced walls, one of which is apertured, which extends around the conveyor path.

United States Patent 1 Stievenart 51 Feb. 20, 1973 [54] PHOTOGRAPHIC DRYER [75] Inventor: Emile Frans Stievenart, Mortsel,

Belgium [73] Assignee: Gevaert-Agia N.V., Mortsel, Belgi- 22 Filed: March 10,1971

21 Appl.No.: 122,693

[30] Foreign Application Priority Data March 11, 1970 Belgium ..49970 [52] US. Cl. ..34/160, 34/114, 34/155 [51] Int. Cl ..F26b 13/00 [58] Field of Search ..34/l14, 115,155, 160

[56] References Cited UNITED STATES PATENTS 6/1915 Fosbraey ..34/155 X 6/1969 Dhane ..34/l55 X Tetzlaff et al. ..34/l55 Fleissner et al ..34/1 15 Primary ExaminerCarroll B. Dority, Jr. Attorney-William J. Daniel [57] ABSTRACT Dryer for continuous web material including conveyor means extending in a generally circular, preferably helical, path and supporting the material on one side from movement along such path, a drying air plenum extending along a substantial portion of the conveyor path and having a wall lying in generally closely spaced parallel relation to such path portion with apertures in the wall for directing air onto the web material supported on the conveyor, an air current generator for supplying air to the plenum. Preferably,

the plenum is in the form of an annular chamber defined by two spaced walls, one of which is apertured, which extends around the conveyor path.

8 Claims, 4 Drawing Figures PATENTED FEB 20 I373 SHEET 1 OF 3 PATENTEDFEBZOIW 3,716,926

SHEET 2 BF 3' Fig. 2

PATENTED FEBZO ms SHEET 3 OF 3 27 F l'g, 4

PHOTOGRAPHIC DRYER This invention relates to a device for drying web-like material having been subjected to a wet process, and more particularly for continuous drying suchlike photographic material.

The continuous drying of web-like photographic material has already been propounded by means of the device disclosed in Belgian Pat. No. 710,491. This device is provided with opposed mutually co-operating tracks, located so as to define a winding path for receiving and guiding opposed margins of a web, and means for moving the web along such tracks, said means having at least one pair of members provided with a continuous peripheral surface which projects into one of said tracks from one side of the web path at a locus along said path, each member being suitably mounted to move its peripheral surface around an axis extending substantially transversely to the path at said locus, and the members of said pair being so arranged in respect to one another that the distance separating the nearest points on their peripheries is slightly less than the width of the web being fed, whereby the web in said tracks is frictionally engaged at its ectreme side edges by the peripheral surfaces of said members, and driving means for moving said members in order to move said peripheral surfaces in a direction corresponding to the direction of travel of the web along said tracks to thereby advance said web.

It has been proposed to use the device according to Belgian Pat. No. 710,491 not only for developing, fixing and rinsing films, but also for drying the wet processed film continuously. To this purpose heated air was circulated in a device of the kind, the air being blown from one side over the film. Due to this fact the fluid retained on the film surface by adsorption evaporates first, whereupon the moisture adsorbed through the emulsion layer of the film evaporates progressively. In consequence thereof the tackiness of the emulsion layer reaches a maximum value at some time in the drying process and the friction between the film edges and guide-tracks increases accordingly.

Furthermore, the passing from the wet to the dry state greatly disturbs the equilibrium of forces acting on both sides of the film and the latter will show a strong tendency to become bent in the transverse direction. In spite of a reinforcement of the film due to bending in longitudinal direction, the transverse bend is not perfectly avoidable and consequently the actual film width is decreased and the contact pressure of the film edges against the rollers is reduced.

The object of the present invention is to provide a drying device which does not show these drawbacks.

According to the present invention, the device for drying moist web-like material comprises an endless belt, means for driving said endless belt in one direction, means for guiding said endless belt along a pre-determined path, means for making the moist weblike material to be dried to contact one side of the endless belt, means for generating an air current and means for directing said air current towards the side of the endless belt bearing the web-like material so as to maintain the web-like material in contact with the endless belt by said air current.

According to a further embodiment of the present invention, the drying device comprises an endless belt which is led along a helical path around a cylindershaped frame, said belt running on freely rotatable small guide-rollers, the distance between two successive guide-rollers being such that the endless belt does not contact said cylinder anywhere, a blower being provided for blowing drying air on the film surface in a direction normal thereto so as to press the film against the belt.

The expression web embraces various kinds of strip-like materials having a length ranging e.g. from 50 cm to 10 m and much more, and a width of e.g. 8

mm to mm or more.

The invention will be further illustrated by the following example with reference to the attached drawings, of which FIG. 1 is a perspective view of an embodiment of the device according to the invention;

FIG. 2 is a diagrammatic longitudinal section of the device according to FIG. 1;

FIG. 3 is a diagrammatic cross section of the device according to FIG. 1 and FIG. 4 is a section of the guide-tracks for the weblike material.

The drying device 10 according to the invention comprises an air-tight housing 11 and a stationary cylinder 12 inside of same. Inside of said cylinder 12 a substantially cylindrical frame 17 is stationarily mounted, whereon a set of freely rotatable small guiderollers 14 are mounted along a helical path. An endless belt 15 runs around and along the set of small guiderollers 14 and is driven at the outside of the housing 1 l by means of e.g. a driving roller 16. Between the successive windings of the helical path of the small guiderollers 14 a set of circular holes 18 are provided in said frame 17. In said cylinder 12 rectangular blowing slots 13 are arranged along the helical path opposite to said belt 15.

The housing 11 of the device according to the invention is closed by an air-intake grating 20 at the right side with reference to FIGS. 1 and 2. To the left with reference to FIGS. 1 and 2 the housing 11 is closed by the cylinder 12. Said cylinder is closed on the opposite side by a conical screen 21. To the right of the conical screen 21 with reference to FIGS. 1 and 2 a motor 22 driving a blower 23 is provided. Between the blower 23 and the air-intake grating 20 a heating resistor 24 is provided in order to heat the air sucked in by said blower 23.

On said cylinder 12 a helical inclined rib 19 (with reference to FIG. 2) may be provided between successive windings of the helical-shaped set of blowing slots 13. The height of the rib 19 increases in the direction away from the blower, The rib 19 provides for the control of the pressure and the space distribution between the housing 11 and the cylinder 12 so that the air for drying may be uniformly distributed over the air blowing slots 13.

Web-like photographic material, e.g. a wet photographic film 25 is fed via a feed line, shaped as a pair of guide-tracks (with reference to FIGS. 3 and 4) onto the endless belt 15. FIG. 4 shows a cross section of the feed line. Said film feed line consists of two tracks 26 located at a distance of one another, which are provided with grooves 27 facing each other, between which it is possible for film 25 to move while it is supported at its margins.

The operation of the embodiment illustrated in FIG. 1 to 3 is as follows. By means of the guide-tracks 26,, the photographic film 25 is applied with the emulsion facing downwards on the continuously moving belt (the face without emulsion being applied to the belt), which runs over the guide-rollers 14 through an aperture in the housing 11 and the cylinder 12. Said guide-tracks 26 may end outside the housing 11 as illustrated in FIG. 3 and the front end of the film must be sufficiently stiff in longitudinal direction to enter the housing 11 and the cylinder 12. If the film 25 is not stiff enough in the longitudinal direction it is possible to make the guidetracks 26 continue as far as the interior of the cylinder 12, or to guide the endless belt 15 to the top of the cylinder 12, e.g. by turning the arrangement of FIGS. 1 and 3 upside down. The path followed by the drying air is diagrammatically shown in FIG. 2. The air sucked in via the air'intake grating by the blower 23 is heated by the heating resistor 24 and led to the blowing slots 13. The drying air comes out substantially in a radial direction from the blowing slots 13 and presses said film 25 on the endless belt 15. In this way the film is simultaneously dried and conveyed through the device 10. The moist air escapes via the holes 18 of the frame 17 to the atmosphere.

From FIG. 1 and 3 it appears that after passing four times around the frame 17 the endless belt 15 runs at the underside of the device 10 through an aperture in the cylinder 12 and the housing 11 and is led back outside the housing 11 on small guide-rollers 28 placed along a helical path to the spot where the film enters the device 10 according to the invention and is conveyed back to said endless belt through an aperture in the housing 11. For the sake of clearness one guideroller 28 has been omitted in FIG. 1.

In this way an efficient continuous drying of the film is achieved in the absence of any contact with the emulsion side of the film.

Characteristics of an actually operating device Speed of film 6 m/min. Width of endless belt 60 mm Width of film 16 or mm Diameter of housing 750 mm Number of windings of the endless belt around frame four Air-flow 5 m3/scc Output (blower) L6 Kw (380 Volts) Heater resistor 6 Kw (220 Volts) What we claim is:

1. Device for continuous drying moist web material comprising:

a. an endless belt,

b. means for driving the belt in one direction,

0. an array of small guide rollers arranged in a helical path for guiding the endless belt along said path, means for feeding the moist web material in to contact with one side of the endless belt,

. means for generating an air current,

means for directing said air current towards the side of the endless belt bearing the web material so as to urge the web material into contact with said belt. 2. Device according to claim 1, wherein means are provided for heating said air current.

3. Device according to claim 1,wherein said means for directing the air current comprises a set of blowing slots arranged along a helical path opposite to said endless belt in a stationary cylindrical wall provided around said guide rollers.

4. Device according to claim 1, wherein the means for directing the air current comprises two spaced walls in the vicinity of a portion of the path followed by the endless belt, the wall facing said endless belt being provided with egress apertures for said air current and is directed towards the side of said endless belt, carrying the web material.

5. Device according to claim 4, wherein said walls are formed by two co-axial cylinder walls defining an annular space which is closed at one end while the opposite end communicates with means for generating said air current.

6. Device according to claim 5 wherein the inner coaxial cylinder wall is provided on its exterior face with a helical upstanding rib located between the successive windings of the endless belt.

7. Device according to claim 6, wherein the height of the helical rib increases towards the closed end of the annular space.

8. Device according to claim 6, wherein the rib is inclined towards the means for generating the air current. 

1. Device for continuous drying moist web material comprising: a. an endless belt, b. means for driving the belt in one direction, c. an array of small guide rollers arranged in a helical path for guiding the endless belt along said path, d. means for feeding the moist web material into contact with one side of the endless belt, e. means for generating an air current, f. means for directing said air current towards the side of the endless belt bearing the web material so as to urge the web material into contact with said belt.
 1. Device for continuous drying moist web material comprising: a. an endless belt, b. means for driving the belt in one direction, c. an array of small guide rollers arranged in a helical path for guiding the endless belt along said path, d. means for feeding the moist web material into contact with one side of the endless belt, e. means for generating an air current, f. means for directing said air current towards the side of the endless belt bearing the web material so as to urge the web material into contact with said belt.
 2. Device according to claim 1, wherein means are provided for heating said air current.
 3. Device according to claim 1, wherein said means for directing the air current comprises a set of blowing slots arranged along a helical path opposite to said endless belt in a stationary cylindrical wall provided around said guide rollers.
 4. Device according to claim 1, wherein the means for directing the air current comprises two spaced walls in the vicinity of a portion of the path followed by the endless belt, the wall facing said endless belt being provided with egress apertures for said air current and is directed towards the side of said endless belt, carrying the web material.
 5. Device according to claim 4, wherein said walls are formed by two co-axial cylinder walls defining an annular space which is closed at one end while the opposite end communicates with means for generating said air current.
 6. Device according to claim 5 wherein the inner co-axial cylinder wall is provided on its exterior face with a helical upstanding rib located between the successive windings of the endlEss belt.
 7. Device according to claim 6, wherein the height of the helical rib increases towards the closed end of the annular space. 